In Lyle’s entertaining if uneven sequel to 2017’s The Irregular, it’s 1910 and the new British Secret Service is up and running with Vernon Kell heading domestic operations and Wiggins, a former Baker Street Irregular, as his sole investigator. When Kell is tasked with probing high-level leaks that benefit Germany, Kell must consider some of the government’s most powerful officials as potential sources. Rival agencies are trying to shut Kell’s office down, Home Secretary Winston Churchill demands a loan of Wiggins’s services, and Kell’s suffragist wife, Constance, is hiding secrets. Meanwhile, Wiggins is also helping a friend look for a missing 18-year-old girl. Wiggins’s search leads him to the so-called Embassy of Olifa, actually an elite brothel engaged in not just sexual but also violent crimes. The rapid switching early on between story lines and secondary characters can be confusing, but later scenes between the irrepressible but infallible Wiggins and Constance, who shares his remarkable gift for detection, are clever and witty. Readers will hope to see plenty more of Wiggins. (Nov.)